Metaplastic carcinoma of the breast with transformation from adenosquamous carcinoma to osteosarcomatoid and spindle cell morphology

Primary squamous cell carcinoma of the breast: a case report

INTRODUCTION

Squamous cell carcinoma (SCC) of the breast is a rare variant of invasive breast cancer that has been classified as metaplastic carcinoma. When a tumor is composed of spindle cells, diagnosis is challenging.

CASE REPORT

A 42-year-old woman with a large mass in the right breast underwent modified radical mastectomy. A pathological examination revealed a tumor with central necrosis in it. The tumor had a sarcomatoid growth pattern and the cells were spindle-shaped with severe atypicality. Immunohistochemical staining showed that P63, P53, vimentin, and CKpan were positive, whereas estrogen receptor and C-erbB-2 were negative. Ki-67 proliferation index was as high as 90%. Therefore, a diagnosis of SCC of the right breast was made. The patient received eight cycles of postoperative chemotherapy with paclitaxel and carboplatin, followed by seven cycles of radiotherapy. During follow-up, the patient also had a left thyroid tumor, and postoperative pathology suggested microinvasive follicular carcinoma. Since breast surgery, the patient has remained disease-free for more than four years.

CONCLUSION

SCC of the breast with spindle cell and sarcomatoid features is rare. The diagnosis of such tumors requires exclusion of tumors with similar histological morphologies.

Metaplastic Carcinoma of the Breast: Case Series of a Single Institute and Review of the Literature

Metaplastic carcinoma of the breast (MpBC) is a very rare and aggressive type of breast cancer. Data focusing on MpBC are limited. The aim of this study was to describe the clinicopathological features of MpBC and evaluate the prognosis of patients with MpBC. Eligible articles about MpBC were identified by searching CASES SERIES gov and the MEDLINE bibliographic database for the period of 1 January 2010 to 1 June 2021 with the keywords metaplastic breast cancer, mammary gland cancer, neoplasm, tumor, and metaplastic carcinoma. In this study, we also report 46 cases of MpBC stemming from our hospital. Survival rates, clinical behavior, and pathological characteristics were analyzed. Data from 205 patients were included for analysis. The mean age at diagnosis was 55 (14.7) years. The TNM stage at diagnosis was mostly stage II (58.5%) and most tumors were triple negative. The median overall survival was 66 (12-118) months, and the median disease-free survival was 56.8 (11-102) months. Multivariate Cox regression analysis revealed that surgical treatment was associated with decreased risk of death (hazard ratio 0.11, 95% confidence interval 0.02-0.54, p = 0.01) while advanced TNM stage was associated with increased risk of death (hazard ratio 1.5, 95% confidence interval 1.04-2.28, p = 0.03). Our results revealed that surgical treatment and TNM stage were the only independent risk factors related to patients' overall survival.

Recurrent Metaplastic Breast Cancer with Subtype Converted from Triple-Negative to HER2-Positive: A Case Report and Literature Review

Background

Metaplastic breast cancer (MBC) is an extremely rare malignant breast disease that has rarely been reported. The molecular subtype of MBC is mostly triple-negative, with a high recurrence rate and a worse prognosis. Due to its low HR- and HER2-positive rate, reports on endocrine and targeted therapy are very limited.

Case report

We report a case of infrequent triple-negative MBC, which, although at an early stage, quickly developed multiple recurrent lesions in the chest wall. The tumor relapsed repeatedly after comprehensive treatment, including surgery, chemotherapy and radiotherapy. However, pathological results after the third surgery suggested that the molecular subtype had changed from triple-negative to HER2-positive. The previous comprehensive treatment had not been able to effectively control the disease, but the patient achieved a long progression-free survival time through chemotherapy and trastuzumab targeted therapy after the subtype change. To date, there has been no recurrence for over eight years.

Conclusion

Among repeatedly relapsed MBC patients, further investigation should be taken into consideration. As in the case presented in our study, it is possible that the HER2 status can convert from negative to overexpression. Moreover, for HER2-positive MBC patients, anti-HER2 therapy is recommended. The decision-making process requires multidisciplinary involvement.

Breast lesions with myoepithelial phenotype

Myoepithelial cells (MECs) constitute a continuous layer of cells surrounding the breast glands, localised between the epithelial cells (ECs) and the basal membrane. MECs play important roles in normal mammary gland as they produce basal membrane and stimulate secretion. During neoplastic transformation, MECs act as a barrier preventing stromal invasion. MECs themselves can undergo a great variety of changes, ranging from hyperplastic to metaplastic, to neoplastic, and giving rise to a wide spectrum of morphological pictures sometimes difficult to interpret on routine diagnoses. Several benign and malignant breast tumours can present features of MECs differentiation. As these latter tumours are quite infrequent, the purpose of the present study is to offer a review of the morphological spectrum of MECs lesions, with correlations to prognosis.

Breast carcinomas of low malignant potential

Some breast carcinomas have a very low likelihood of metastasis to regional lymph nodes and distant sites and may be considered carcinomas of low malignant potential. In this article, we review the clinical, pathologic, immunophenotypic, and molecular features of selected breast carcinomas of low malignant potential including low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, encapsulated papillary carcinoma, solid papillary carcinoma, and tall cell carcinoma with reversed polarity.

Subcellular localization of EZH2 phosphorylated at T367 stratifies metaplastic breast carcinoma subtypes

BACKGROUND

Metaplastic carcinoma is an aggressive, triple-negative breast cancer (TNBC) with differentiation towards squamous, spindle, or mesenchymal cell types. The molecular underpinnings of the histological subtypes are unclear. Our lab discovered a cytoplasmic function of EZH2, a transcriptional repressor, whereby pEZH2 T367 binds to cytoplasmic proteins in TNBC cells and enhances invasion and metastasis. Here, we investigated the expression and subcellular localization of pEZH2 T367 protein in metaplastic carcinomas.

METHODS

Thirty-five metaplastic carcinomas (17 squamous, 10 mesenchymal, and 8 spindle) were evaluated and immunostained with anti-pEZH2 T367. We analyzed staining intensity (score 1-4), subcellular localization (nuclear/cytoplasmic), and localization within the tumor (center/invasive edge). Protein expression of pEZH2 T367-binding partners was measured from a quantitative multiplex proteomics analysis performed in our lab.

RESULTS

Cytoplasmic pEZH2 T367 was significantly upregulated in squamous (14 of 17, 82%) compared to mesenchymal (4 of 10, 40%) and spindle (2 of 6, 33%) subtypes (p = 0.011). Twenty-five of 34 (73%) tumors with available tumor-normal interface showed accentuated cytoplasmic pEZH2 T367 at the infiltrative edge. Cytoplasmic pEZH2 T367 was upregulated in 9 of 10 (90%) tumors with lymph node metastasis (p = 0.05). Bioinformatics analyses identified an EZH2 protein network in metaplastic carcinomas (p value: < 1.0e-16). Using quantitative proteomics, we found significantly increased expression of cytoplasmic EZH2-binding partners in squamous compared to spindle and mesenchymal subtypes.

CONCLUSIONS

pEZH2 T367 expression and subcellular localization may be useful to distinguish metaplastic carcinoma subtypes. pEZH2 T367 may play a role in the histological diversity and behavior of these tumors.

A Comparative Review of Mixed Mammary Tumors in Mammals

Mixed tumors are characterized by the histological identification of two or more cell types. Commonly, a mixture of epithelial and myoepithelial cells is included in abundant stroma, which can consist of myxoid, chondroid or bony matrices. Spontaneously arising mixed tumors are rare lesions in the human breast but are common in human salivary glands and canine mammary glands. Subtle histopathological characteristics and overlapping attributes of malignant lesions with other benign lesions can lead to a diagnostic challenge. Mixed tumors can present as benign or malignant. While malignant mixed tumors are quite rare in the human breast they have a poor prognosis. Benign mixed mammary tumors occur more frequently in female dogs than in humans and are usually associated with a good prognosis. This review will provide a comprehensive overview of mixed mammary tumors, across various mammalian species.

Metaplastic carcinoma of the breast

Metaplastic carcinoma of the breast is a rare but aggressive type of breast cancer that has been recognized as a unique pathologic entity by the World Health Organization. Morphologically, it is characterized by the differentiation of neoplastic epithelium into squamous cells and/or mesenchymal-looking elements (squamous cells, spindle cells, cartilage or bone, etc). It shares many similarities with invasive ductal carcinoma and benign lesions on mammography, which further complicates the diagnosis. Treatment for metaplastic breast carcinoma is relatively unknown because of the rarity of the disease, but studies suggest that removal of the tumor and adjuvant radiation therapy has the greatest benefit.

Bilateral synchronous low-grade adenosquamous carcinoma of the breast: A Case report with review of the current literature

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LGASC is an uncommon form of triple-negative metaplastic breast carcinoma.

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Imaging, FNAC, & CNBx are usually indeterminate with no pathognomonic features.

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Histopathology is the gold standard for definitive diagnosis.

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Relationship between LGASC and benign mimickers (SAN, CSL) continues to evolve.

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LGASC is likely multicentric, thus mastectomy is the recommended management.

Introduction

Low-grade adenosquamous carcinoma (LGASC) is a rare, unique variant of metaplastic breast carcinoma, characterized by clinical indolence and low-grade cytomorphology. Being clinically asymptomatic with indefinite imaging characteristics, diagnosis is solely dependent on histopathology.

Presentation of Case

A 68-year-old woman presented to the Breast Health Center with mammogram-detected left-sided retroareolar calcifications. She had a three-year history of non-progressive bilateral nipple inversion, and was otherwise asymptomatic. Left breast biopsy revealed atypical metaplastic squamous epithelial cells. Subsequently a wire-guided lumpectomy diagnosed a syringomatous adenoma of the nipple. A surveillance MRI identified a contralateral breast lesion, which on core biopsy showed an atypical adenosquamous lesion. Bilateral central mastectomies with bilateral sentinel node biopsies were undertaken.

Histopathological review of both breast specimens confirmed the unique features of adenosquamous carcinoma identified by an infiltrative pattern of small rounded compressed angulated glands with squamous differentiation and low-grade cytomorphology. The tumors were triple negative [ER, PR, HER2]. The sentinel lymph nodes were negative.

Conclusion

Bilateral synchronous LGASC of the breasts is exceedingly uncommon and remains a diagnostic and therapeutic challenge. Despite being triple negative, due to its indolent behavior, recognition of this unusual primary breast malignancy is important as it has a more favorable prognosis. Yet, due to its rarity, there are no guidelines for best practice management regarding the role of adjuvant therapy.

Adenosquamous proliferation of the breast and low grade adenosquamous carcinoma: a common precursor of an uncommon cancer?

Low grade adenosquamous carcinoma (LGASC) is rare but commonly reported to arise in association with benign proliferative and sclerosing breast lesions which themselves may show associated sclerosing or 'adenosquamous proliferation' (ASP) resembling LGASC, but are often derided as reactive mimics or attributed to earlier biopsy. Among other benign lesions, radial sclerosing lesion (RSL) may be associated with LGASC, yet attention is typically focused on its relationship to more common forms of mammary carcinoma. This study aimed to assess the presence and extent of ASP in the context of RSL in a small cohort of 20 cases and its similarity to LGASC.Twenty consecutive breast excisions that had a principal or incidental diagnosis of RSL were reviewed. RSLs that displayed foci of ASP were further examined with immunohistochemical markers for p63, calponin, cytokeratin 5/6, oestrogen and progesterone receptors.Sixty percent of excisions contained ASP either associated with a RSL or a concurrent papilloma, which morphologically and immunohistochemically were indistinguishable from the neoplastic ducts of LGASC. RSL with and without ASP broadly corresponded to accepted definitions for 'early' and 'late' lesions, respectively. ASP corresponded to the characteristic compact branching ducts of the core or nidus of a RSL.The morphological and immunophenotypic similarity of the ASP found in RSL and papillomata to LGASC warrants serious consideration that they are a potential precursor to LGASC, which may most commonly involute given the rarity of clinically apparent LGASC. Further study including micro-dissection of foci of ASP to compare its molecular genetic profile to that of LGASC is required.

Metaplastic breast carcinoma: a heterogeneous disease

The aim of this study is to evaluate clinicopathologic characteristics and the multi-disciplinary treatment results of metaplastic breast cancer (MBC) patients treated in a single institute. Seventeen female patients with MBC treated in our department between June 2000 and January 2012 were identified and retrospectively evaluated. The median age at diagnosis was 46 years (range, 26-66 years). The median tumor size at diagnosis was 3.5 cm (range 1.5-12 cm). Six (35%) patients underwent breast conservation surgery and 11 (65%) mastectomy. Axillary lymph node metastasis was found in 6 (35%) patients. Twelve (71%) had triple negative tumors. Postoperative RT and systemic adjuvant treatment was given to all patients accordingly to stage and biological characteristics. Median follow-up time was 27 months (range, 12-151 months). At the time of this analysis, 14 (82%) patients were alive with no evidence of disease, and 1 (6%) was alive with disease. The 3-year OS was 91% and 5-year 80%, and DFS rates were 76% and 76%, respectively. Despite the young age of our patients with mostly high grade tumors, larger tumor size and higher rates of lymph node metastasis, the survival outcomes in our study are favorable in comparison with previously reported series.